"In engineering, it is important to design a machine for the most economical functioning, and to build it as cheaply as possible. The underlying principle is to be economical with resources both in the construction process and in the operation of the machine. Is it also a principle in biology to build organisms economically, not to waste resources and to achieve the least expensive operation?" (p. 12)

In this highly technical, initial book length treatment of the subject of symmorphosis Weibel attempts to show that animals are "designed" economically. He also paves the way for further research on the subject with ideas about how to do so.

Outside of the first and last chapters, readers are feed little besides the details of quantitative studies performed on cells, tissues, muscles, organs (especially the lungs), and blood vessels. Few will want to get into the details of the middle chapters. They can be quite dense. They also seem to function as a sort of smoke screen to the problems of the theory. How can something not be correct when we have so many numbers to support it? Right? Wrong. At least sometimes wrong.

Not to suggest that symmorphosis is dead in the water or doesn't have much truth to it, but as defined in the Preface, symmorphosis simply isn't going to always be the case. It will never be a scientific theory with universal application. That definition is

that the quantity of structure incorporated into an animal's functional system is matched to what is needed: enough but not too much. (p. xii)

In our world of natural selection this seems to make sense--at least on the surface. If a functional system doesn't have "enough" of something then natural selection will drive the species to the point of having enough. However, natural selection isn't perfect and genetic drift happens. Natural selection can be slow. It can be behind the times and the current environment. And it can only work with what it is initially given or with what it has already developed. These factors alone should be enough for the pioneers in the field to change the definition of symmorphosis to something a little more flexible and much less exact. However, it isn't until some very short disclaimers near the end of the book that Weibel admits the possibility of exceptions and pitfalls of his theory.

Early on Weibel claims that "cells are designed economically" and that it is an established "principle that cells do not burden themselves with baggage they don't need." (p. 14) While this is partially true, it does still ignore the fact that there is "too much" of some things at the cellular level thanks to the cumulative nature of evolution. For instance, most DNA is "junk", otherwise known as pseudogenes, and can hardly be called or considered economical. On the macro scale, vestigial organs and other body parts are completely ignored. Evolution tends to get around to removing or converting such things, but it takes numerous generations to weed out these inefficiencies. Symmorphosis should include, rather than turn a blind eye to, items like these and incorporate them into a working, flexible framework.

Another possible methodological error committed is the apparent attribution of everything an animal is to its genes. For instance, the section between and including pages 47-50 doesn't determine whether the differences in mitochondria per muscle is caused mostly by genes or the environment (including exercising). Fast running animals (including only some athletic humans) have higher mitochondria counts. So what? Are they "designed" that way via evolution or did they get that way by running fast and often? We don't know whether the people were born athletes or whether they became such through training. Without answering this question the design element of symmorphosis theory seems to go out the window. The experiment would be a simple one (albeit unnatural and perhaps unethical and cruel). Raise one of the pronghorn (shown on the book cover and used in many of the examples) in captivity and don't allow it to exercise. Then compare its mitochondria count with the domesticated goats (which is the other animal it is compared to in the book) and the mitochondria counts of wild pronghorn who are running on a daily basis.

At the conclusion of an experiment (involving O2 pathways), the results "find that no excess structure is maintained." (p. 208) That may, or may not, be true for the case at hand, but it certainly doesn't have universal application. George Williams wrote a book that focuses almost entirely on the waste that we can easily find in organisms. Others have found waste and excess structure in the neuroanatomy. The list could go on and on.